How do I open my inventory in Cyberpunk 2077?

I’m at the first main combat section of the game and all I have is a pistol. I’ve killed a guy and picked up his machine gun, but I can’t seem to find the key to open my inventory to equip it.

Is there an inventory that lets me equip the weapon? If so, what’s the default keybinding?

Edit: I should clarify that pressing I doesn’t work. And opening the keybinds shows the controller